De BGLfXdKkdTB7 Le 14/12/2013 - 13:45
How do I know how many isotopes an elnmeet has? Like is there a way to figure out Chlorine has two isotopes? or are we given this information some of the mastering chemistry questions ask about this and I wasn't sure if we were just supposed to look it up on the internet or know somehow? Thanks!
De YuZ7W2ei Le 14/12/2013 - 12:56
In nature, elmneets occur as a mixture of isotopes. What we report on the periodic table is the average atomic mass of the elmneets isotopes. In order to calculate this number we need to know a few things: How many isotopes exist, the mass of each isotope, and the relative abundance of each isotope. I think what you are trying to get at here is that can we run every single, say chlorine atom on the earth through a mass spectrometer? We don't but we can use statistics to report values to several decimal places. Remember that one mole of chlorine contains 6.022 x 1023 chlorine atoms. That's a heck of a lot of atoms. So 6.022 x 1023 chlorine atoms weighs 35.453 grams. What if we took away just one chlorine atom? Would the mass change appreciably? How about if we were 10 chlorine atoms less than 6.022 x 1023? We will definitely discuss this tomorrow in class.
De f3Q9f8mpiDjN Le 14/12/2013 - 11:48
Uranium is radioactive, it iusesd in Nuclear reactors and is used to power aircraft carriers, and submarines.It is extremely radioactive and is why it is not used to power vehicles, however it is possible.IT would not be cost effective. Uranium ( /jʊˈreɪniəm/ yew-RAY-nee-əm) is a silvery-white metallic chemical element in the actinide series of the periodic table with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. The uranium nucleus binds between 141 and 146 neutrons, establishing six isotopes, the most common of which are U-238 (146 neutrons) and U-235 (143 neutrons). All isotopes are unstable and uranium is weakly radioactive. Uranium has the second highest atomic weight of the naturally occurring elements, lighter only than plutonium-244.[3] Its density is about 70% higher than that of lead, but not as dense as gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite.In nature, uranium is found as uranium-238 (99.2742%), uranium-235 (0.7204%), and a very small amount of uranium-234 (0.0054%). Uranium decays slowly by emitting an alpha particle. The half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years,[4] making them useful in dating the age of the Earth.
De GemBgG1lq Le 14/12/2013 - 11:19
Salaam Fawzy,Thank you for your post! I too feel the 15, 16 and 17th juz hold a special place, eslleiapcy surah Maryam and Kahf. It is like your example of the dhikr routine and how you can never run out of blessings to count, you can never run out of wisdoms to extract from these chapters. I'm going to try out your dhikr tip the next time I have an extended amount of downtime, inshaAllah. Thanks for sharing
De lQXC06x7d Le 14/12/2013 - 11:06
I really liked that snatemett about not wanting to be rich too Jackie. I think the motivation to save can be perceived as greed sometimes when that's usually not the case. Being responsible with our financial resources allows us security and freedom. When we have financial security and freedom, we're better able to make a positive impact. If we're just trying to survive, we spend our energy and time trying to make ends meet rather than having the opportunity to choose a more harmonious path and ultimately give back!
De wSrFf43k17 Le 14/12/2013 - 10:55
maybe this should be a nice leossn for western people to re-think before make any jokes or humours. without using brain, surely not laughs which will be created, but 1.3 million dollars per-day loss.like waht happen in arlafoods now.Choi Beijing
De bAIKkbxeNTqU Le 14/12/2013 - 10:44
Guess the Saudis won't be able to eat those delicious Danish hams anmyroe! And, no more Carlsberg or Tuborg!!! (There's nothing quite like a Ham & Swiss sandwich accompanied by a chilled Danish beer-- especially after a long hot day looking for oil in the Saudi desert).On a more serious note: I intend to look over that list, and make a shopping list of things I will personally buy to support free speech-- and email a message to people I know.
De 3jhtCXQa Le 14/12/2013 - 09:40
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De Tci8YzQ0tO Le 14/12/2013 - 06:29
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De lE441JaAkj8 Le 14/12/2013 - 06:06
The Absent Game Amongst me and my husband we have owned far more MP3 geamrs over the years than I can count, which includes Sansas, iRivers, iPods (traditional & touch), the Ibiza Rhapsody, etc. But, the last few several years I've settled down to one line of players
De NPLPPcukpI8 Le 14/12/2013 - 05:40
Sans conteste, le plus etiiaordxnarre poe8me de Tamim al Barghouti et Dieu sait pourtant, si l'on avait aime9 ceux sur al Qods ou celui racontant la trage9die irakienne. Les poe8tes nous sauvent de la me9diocrite9 ambiante!!!
De wNeRRyYPKZ4a Le 14/12/2013 - 05:33
Magistral et poignant, e0 trveras ces vers lourds de sens, la confiance en la ve9rite9 et au combat s'impose entre les lignes. Mais seul un coeur sain et libre peut re9pondre e0 l'appel, pur, de la dignite9 ...
De knlRkquqNZ7y Le 13/12/2013 - 15:54
I hate my life but at least this makes it beraebla.
De LuJyDGWmX273 Le 13/12/2013 - 14:28
Your's is the inelnligtet approach to this issue.
De 2zAt8WbOK4 Le 13/12/2013 - 09:46
It's a plauesre to find someone who can think so clearly
De fXX1o1RRlC Le 13/12/2013 - 09:38
Your answer was just what I nedeed. It's made my day!
De 08jwF4ed9o Le 13/12/2013 - 09:17
So excited I found this article as it made things much quikrec!
De eaV9ohhg Le 13/12/2013 - 08:55
Good to find an expert who knows what he's taiklng about!
De mg5eOgzC9 Le 13/12/2013 - 07:43
I could watch Schlrdien\'s List and still be happy after reading this.
De 2aovpT5GfDd Le 13/12/2013 - 07:08
This "free sharing" of infoomatirn seems too good to be true. Like communism.